Shopify performance: common issues and how to fix them

Why Shopify stores slow down

Shopify stores often slow down over time [2]Source 2 . Apps pile up, themes get patched, tracking scripts spread, and mobile takes the hit first.

For more on Shopify support and performance fixes, see Shopify expertise.

Common performance issues

1) Theme bloat

Themes can include code and assets you do not use. Over time, patches and customisations add more code.

• Unused features: Themes include features you may not need.
• Patched code: Customizations and patches add code on top of the theme.
• Oversized bundles: CSS and JavaScript bundles that are larger than needed.

For more on theme performance, see themes vs bespoke builds.

2) App bloat

Apps add functionality, but they also add code, scripts, and requests. Too many apps can slow down your store.

• Duplicate features: Multiple apps doing similar things.
• Heavy scripts: Apps that load large JavaScript files.
• Render blocking: Apps that block page rendering.

Remove unused apps and consolidate features where possible [2]Source 2 .

3) Third-party scripts

Tracking scripts, pixels, and analytics can add significant weight [5]Source 5 .

• Multiple trackers: Facebook Pixel, Google Analytics, Google Tag Manager, and more.
• Early loading: Scripts that load before critical content.
• Unnecessary scripts: Scripts you no longer use or need.

Review and remove unnecessary scripts. Load remaining scripts later where safe.

4) Image handling

Product images are essential, but they can slow down pages if not handled well.

• Unoptimised images: Large image files that take time to load.
• Too many images: Loading all product images at once.
• Missing lazy loading: Images that load even when not visible.

Optimise images, use modern formats, and lazy load where appropriate.

5) Checkout speed

Slow checkout can cost sales. The checkout process should be fast and smooth.

• Heavy checkout scripts: Scripts that slow down the checkout process.
• Unnecessary fields: Fields that are not required but slow down completion.
• Payment processing delays: Slow payment processing or validation.

Optimise checkout for speed and remove unnecessary friction.

How to fix performance issues

1) Audit your store

Start by understanding what is slowing down your store.

• Shopify web performance reports: Use Shopify's built-in performance reports [1]Source 1 .
• Core Web Vitals: Check LCP, INP, and CLS [4]Source 4 .
• Template checks: Test individual templates for performance issues.

For more on audits, see performance audit outcomes.

2) Reduce app bloat

Remove unused apps and consolidate features.

• Review apps: List all installed apps and identify what you actually use.
• Remove unused apps: Uninstall apps you no longer need.
• Consolidate features: Use fewer apps that do more, rather than many apps that do one thing each.

3) Optimise theme code

Clean up theme code and remove unused features [3]Source 3 .

• Remove unused code: Delete code for features you do not use.
• Fix render blocking CSS: Inline critical CSS, defer non-critical styles.
• Optimise bundles: Reduce CSS and JavaScript bundle sizes.

4) Trim third-party scripts

Review and optimise third-party scripts [5]Source 5 .

• Remove unnecessary scripts: Delete scripts you no longer use.
• Load scripts later: Defer non-critical scripts until after page load.
• Consolidate trackers: Use fewer tracking tools where possible.

5) Improve image handling

Optimise product images and media.

• Optimise images: Compress images, use modern formats (WebP, AVIF).
• Lazy load: Load images only when they are about to be visible.
• Responsive images: Serve appropriately sized images for each device.

For more on images, see image and video performance.

6) Optimise checkout

Make checkout fast and smooth.

• Minimize fields: Only ask for what is required.
• Optimise scripts: Remove unnecessary scripts from checkout.
• Test checkout speed: Measure and improve checkout performance.

Measuring improvement

Track performance before and after changes.

• Before metrics: Document current performance with specific numbers.
• After metrics: Measure again after changes to see improvement.
• Core Web Vitals: Monitor LCP, INP, and CLS over time.

Shopify web performance reports provide store-level signals and Core Web Vitals [1]Source 1 .

Common wins

Typical improvements from fixing these issues:

• Reduce app bloat: Remove duplicate features and unused apps.
• Trim third-party scripts: Remove unnecessary scripts and load remaining ones later.
• Fix render blocking CSS: Optimise CSS loading to improve LCP.
• Improve image handling: Optimise images and lazy load where appropriate.
• Stop layout shifts: Fix layout shifts from late loading content and banners.

Summary

Common issues: theme bloat, app bloat, third-party scripts, image handling, checkout speed.

How to fix: audit your store, reduce app bloat, optimise theme code, trim third-party scripts, improve image handling, optimise checkout.

Measure improvement: track before and after metrics, monitor Core Web Vitals.

For more on Shopify performance and support, see Shopify expertise. For help with e-commerce, see e-commerce services. For more on small e-commerce sites, see small e-commerce websites. You can also get in touch to discuss your Shopify performance needs.